Calculation of the Primary Current Distribution in Cells with Curved Electrodes Using the Finite Difference, Conservative Scheme, and Finite Element Methods

1996 ◽  
Vol 61 (11) ◽  
pp. 1563-1584
Author(s):  
Josip Zoric ◽  
Ivo Roušar
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Finite Element Methods ◽  
Current Distribution ◽  
Current Density ◽  
Conservative Scheme ◽  
Local Current Density ◽  
Local Current ◽  
Primary Current ◽  
Primary Current Distribution

The primary current distribution was calculated in cells with a curvilinear shape of the electrodes by the finite difference (FDM), the conservative scheme (CS), and the finite element methods (FEM). These methods were used for the solutions of the Laplace equation (LE) for a 2D cross-section of a cell consisting of two concentric cylinders (tubes) as electrodes and the inter-electrode space filled with electrolyte. For this cell the analytical solution of LE is known. The local current density on the approximated shape of the electrodes was calculated. The error in the normalized local current density relative to the mean was 5.2%, 52% or 0.2% with FDM using a 64 o 64 mesh, CS using 64 o 64 mesh or FEM using 969 nodes, respectively. Also the boundary element method (BEM) has been used. With 199 elements at the electrode the error in the normalized current density was 0.2%. Taking into account the simplicity of programming and the possibility of using previously developed modules in other calculations, FEM and BEM showed the best performance.

On the Mathematical Modelling of Diffusion-Migration Mass Transport of Protons

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
José Augusto Ruiz ◽  
Carlos Fernando Zinola
Keyword(s):  
Mass Transport ◽  
Current Distribution ◽  
Current Density ◽  
Electric Potential ◽  
Operation Performance ◽  
Isothermal Model ◽  
Diffusion Migration ◽  
Hydrogen Electrooxidation ◽  
Primary Current ◽  
Primary Current Distribution

A one-dimensional-isothermal model and an analytical solution for the mass transport (migration and diffusion) of protons in a single PEM fuel cell have been developed. Under a linear approximation between current density and electric potential (pseudo-primary current distribution) we have obtained the proton concentration profile along the cathodic and anodic gas diffusers as a function of the position. The graphical shape of the function allows us to discuss the effect of the physicochemical parameters in our model especially on the anodic side of the diffuser. From the dependence of the electric potential and current density with the position we have obtained a theoretical polarization curve. Under the pseudo-primary current distribution, the fitting of the first points yields a high Tafel slope for the cell operation performance. In spite of being a limited model for the cell performance, this is one of the least analytical and exact solved solutions obtained from mass balances in the course of the hydrogen electrooxidation and oxygen electroreduction. We consider that this situation would probably put some more knowledge in the understanding of the PEMFC functional description.

Quasi-simultaneous Mapping of Local Current Density, pH and Dissolved O2

2015 ◽  
Vol 27 (12) ◽  
pp. 2725-2730 ◽  
Author(s):  
Maryna G. Taryba ◽  
M. F. Montemor ◽  
S. V. Lamaka
Keyword(s):  
Current Density ◽  
Local Current Density ◽  
Local Current ◽  
Dissolved O2

Direct Measurement of the Local Current Density Under Land-Channel Areas With Partially-Catalyzed MEAs

2012 ◽  
Author(s):  
Shan Jia ◽  
Hongtan Liu
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Cell Voltage ◽  
Current Density Distribution ◽  
Cathode Side ◽  
High Cell ◽  
Land Area ◽  
Local Current Density ◽  
Local Current ◽  
Voltage Region

In a PEM fuel cell, local current density can vary drastically under the land and channel areas. The non-uniform current density distribution not only affects the overall performance of the fuel cell, but also leads to the local temperature and concentration differentiation on the MEA, which can cause problems such as membrane dehydration and catalyst degradations at certain locations. In order to investigate the local current performance, the objective of this work is to directly measure the local current density variations across the land and channel at the cathode in a PEM fuel cell with partially-catalyzed MEAs. First, the cathode flow plate is specially designed with a single-serpentine channel structure, and the gas diffusion electrode at cathode side is cut to fit this flow field size (5.0cm×1.3cm). Then five different partially-catalyzed MEAs with 1mm width corresponding to different locations from the middle of the gas channel to the middle of the land area are made. Fuel cells with each of the partially-catalyzed MEAs have been tested and the results provide the lateral current density distribution across the channel and the land areas. In the high cell voltage region, local current density is highest under the center of the land area and decreases toward the center of the channel area; while in the low cell voltage region local current density is highest under the middle of the channel area and decrease toward the center of the land area. Different flow rates are tested at the cathode side of the cell to study their effects on the local current density performance along the land-channel direction. And the results show that the flow rate barely has the effect on the current at the high cell voltage region, while it plays a significant role at the low voltage region due to the mass transport effect.

scholarly journals First current density measurements in the ring current region using simultaneous multi-spacecraft CLUSTER-FGM data

2005 ◽  
Vol 23 (5) ◽  
pp. 1849-1865 ◽  
Author(s):  
C. Vallat ◽  
I. Dandouras ◽  
M. Dunlop ◽  
A. Balogh ◽  
E. Lucek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Density ◽  
Ring Current ◽  
Magnetic Activity ◽  
Activity Level ◽  
Local Current Density ◽  
Magnetospheric Configuration And Dynamics ◽  
Local Current ◽  
Current Region ◽  
First Time

Abstract. The inner magnetosphere's current mapping is one of the key elements for current loop closure inside the entire magnetosphere. A method for directly computing the current is the multi-spacecraft curlometer technique, which is based on the application of Maxwell-Ampère's law. This requires the use of four-point magnetic field high resolution measurements. The FGM experiment on board the four Cluster spacecraft allows, for the first time, an instantaneous calculation of the magnetic field gradients and thus a measurement of the local current density. This technique requires, however, a careful study concerning all the factors that can affect the accuracy of the J estimate, such as the tetrahedral geometry of the four spacecraft, or the size and orientation of the current structure sampled. The first part of this paper is thus providing a detailed analysis of the method accuracy, and points out the limitations of this technique in the region of interest. The second part is an analysis of the ring current region, which reveals, for the first time, the large latitudinal extent of the ring current, for all magnetic activity levels, as well as the latitudinal evolution of the perpendicular (and parallel) components of the current along the diffuse auroral zone. Our analysis also points out the sharp transition between two distinct plasma regions, with the existence of high diamagnetic currents at the interface, as well as the filamentation of the current inside the inner plasma sheet. A statistical study over multiple perigee passes of Cluster (at about 4 RE from the Earth) reveals the azimuthal extent of the partial ring current. It also reveals that, at these distances and all along the evening sector, there isn't necessarily a strong dependence of the local current density value on the magnetic activity level. This is a direct consequence of the ring current morphology evolution, as well as the relative positioning of the spacecraft with respect to the bulk of the ring current. It also proves the existence of a substantial ring current at these distances, all over the evening and the post-midnight sector. Keywords. Magnetospheric physics (Current systems; Energetic particles, trapped; Magnetospheric configuration and dynamics)

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